Walk into a restaurant these days and you might be able to check the calorie count of your enchilada, the salt content of your fries, the "heart healthy" status of your asiago peppercorn steak and — in at least one pioneering place — the carbon footprint of your vegetable lasagna.

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More restaurants, either by mandate or by choice, are bombarding diners with calorie counts and other information. The disclosures on menus, menu boards and pamphlets are a victory for health advocates who believe informed consumers will make better food choices.

But the profusion of numbers makes one wonder: Is it possible to give diners too much information about their food?

"At some point, having too much information might actually hurt, because it may start to confuse," says Barry Popkin, a professor of nutrition at the University of North Carolina at Chapel Hill.

Popkin is one of the many advocates who support current laws in New York City, Seattle and elsewhere that require chain restaurants to post calorie counts next to food listings. A similar nationwide requirement was approved recently as part of health care reform. The Food and Drug Administration has a year to write the rules.

At least one city now requires restaurants to divulge even more nutritional information. Philadelphia, home of the Philly cheesesteak, requires chain restaurants to list calories on menu boards, but sit-down chains with written menus must also include information on carbohydrates, sodium, saturated fats and trans fats. Though the narrower federal law will pre-empt local laws, Philadelphia intends to petition for an exemption, says Martha Johnston, a senior attorney for the city.

Even outside Philadelphia many chains will, upon request, provide written nutritional information to customers. A handout nutrition chart at McDonald's includes detailed tables on the saturated fat, cholesterol, sodium, carbohydrates and more for everything from burgers to frappes.

Maybe the most unique drill-down-deep information is provided by Otarian, a vegetarian restaurant with two locations in Manhattan.

Your lunch's carbon footprintEach item on the menu board is listed alongside its carbon footprint, in kilograms, and the footprint of a similar meat dish. For instance, Otarian figures that 1.38 kilograms of carbon are released to make an order of tacos, compared to 2.43 kilograms for beef tacos. The menu board thus informs taco eaters they have saved the release of 1.05 kilograms of carbon into the atmosphere.

Otarian's founder writes about empowering customers to help the environment one meal at a time. It's not clear if all customers use their powers to figure out the carbon numbers.

"I noticed and tried to figure out what they were trying to say with it, but it was kind of confusing," said David Chung, a medical student who ate there recently. "I don't know what saving a kilogram does either."

(For the record: that's roughly the same amount of carbon released by driving a car a few miles).

People who study nutrition and psychology say the rule of thumb for making information useful is to keep it short and sweet — something a person looking up at a fast-food menu board can digest quickly.

Popkin said a good example of what to avoid is are those "Nutrition Facts" labels on packaged foods that are packed with per-serving and daily recommended value information for the likes of fat and fiber. He said the labels are useful — to scientists.

Some chains have just simplified things on their own. "Nothing over 500 calories," says the menu at Energy Kitchen, a health-conscious chain in the New York City area that features burgers and wraps. Seasons 52, a chain operating in seven states, advertises that all the items on its menu — from the shrimp cocktail to the grilled rack of lamb — are under 475 calories. Applebee's promotes its under-550 calorie picks with a little green apple graphic.

With a hodge-podge of local and still-to-be-decided national regulations determining how much and what information consumers will see, it's likely to take time for consumers to get used to seeing numbers other than dollars on the menu.

Jeff Cronin, spokesman for the Center for Science in the Public Interest, a Washington-based nonprofit that has tracked the issue for years, says there is no evidence restaurants are purposely providing too much information in an attempt to confuse consumers.

Does anyone really care?Experts like the simple calories-only approach, but they say it's not a perfect system.

Calorie counts are of limited use to someone who doesn't know how many calories they're supposed to eat a day, says Doug Nelson, director of the Avery Foodservice Research Laboratory at Purdue University. It might be more useful to tell diners that a brownie sundae with 850 calories represents more than a third the daily intake recommended for most adults.

A second problem is the "halo effect," which could lead people to believe that something with low calories is good for them generally. For instance, someone counting calories might consider a lower-calorie chicken and bacon ranch salad a great choice without noticing that its salt count is off the scale.

"It may give the illusion of being better, but without having even more information with extra context, it might not be that much better," says Peter Todd, a professor of cognitive science at Indiana University.

But maybe the biggest weakness of providing information for people ordering food is the "Who cares?" factor. People who order Burger King's Triple Whopper with Cheese (1,250 calories) or Taco Bell's Volcano Nachos (1,000 calories) probably understand that it is not health food.

While some early research has shown calorie counts affect consumer choice, not all studies show that. Even in cities with simple calorie postings, like Albany, N.Y., customers often say they either failed to notice the numbers next to the prices and menu listings — or failed to heed them.

"To me, it's something I ignore," Martin Momodu said as he walked from an Albany McDonald's, biting into a 360-calorie McChicken sandwich. "When I come here, I'm kind of in a rush."

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